Electrify Your Home:
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HOW DO HEAT PUMPS WORK?
Cold-climate heat pumps don’t make heat; instead, they move it from one place to another. A heat pump draws in air from outside a building; refrigeration coolant inside the heat pump absorbs heat from that air, and then the coolant is compressed, which increases its temperature even more. The heated coolant then flows to the indoor unit of the heat pump, and air from inside the building is drawn into the heat pump and absorbs the coolant’s warmth before circulating back out WHY ARE HEAT PUMPS ARE EFFICIENT? Using electricity to circulate coolant and air, and to compress coolant, is much more efficient than forcing it into a resistive heat system like an electric baseboard or a space heater. Those types of systems essentially function by deliberately wasting electricity—converting its energy into heat at a one-to-one ratio, which is to say 100% efficiency. That might sound pretty good ... ... but when you’re using electricity to power a pair of fans, a compressor, and a pump, instead of converting the electricity itself into heat, you can get more than three units of heat out of every unit of electricity, for efficiency rates of over 300% WHAT MAKES HEAT PUMPS CLEAN? Electric devices and systems are, in carbon/climate terms, as clean as the grid that supplies them. So heat pumps aren’t necessarily “clean” heat in and of themselves (though they are still a more efficient use of less-clean electricity than resistive heat systems, of course). However, here in Vermont, according to Energy Acton Network, nearly all greenhouse gas emissions from electricity consumption are due to the fact that we source some of our electricity from a regional system mix through ISO New England. Since 2010, the renewable proportion of that regional system mix has increased—and, even more importantly, since 2017, Vermont has begun pulling less electricity from that source. Overall, Vermont’s electricity sector is rated the least carbon-intensive in the U.S. So, the cleaner your electricity is, the cleaner your heat pump is. And if you combine residential solar with a heat pump, you can guarantee you’re using an even cleaner source than Vermont’s grid. Learn about the different types of heat pumps and considerations for your home in Efficiency Vermont's "Heat Pumps 101" session. Watch the video.
Heat pumps outperform boilers and furnaces by a lot — even in cold climates! Seven field studies across North America, Asia, and Europe show that heat pumps are two to three times as efficient as combustion or resistive electric heating technology, even in temperatures well below 0°C (32º F). In fact they perform significantly better than their fossil fuel-based competitors even in temperatures approaching -30°C (-22º F). CleanTechnica summarizes.
More on the basics of heat pumps: a video from BC Hydro; an article from MIT Technology Review; and an everything-you-need-to-know summary from Energy Sage.
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